Reaching Cancer Survivors with Distance-delivered Support for Physical Activity Behavior Change Cancer is the second leading cause of mortality in the U.S., resulting in over a half a million deaths each year. Furthermore, cancer survivors are more likely to suffer from second cancers, medical comorbidities, and reduced quality of life. Vulnerable cancer survivors (e.g., older, rural residents, underserved) bear a disproportionate burden of suffering after a cancer diagnosis related to greater mortality and poorer health and well-being. Exercise is an important aspect of survivorship care that can reduce this burden of suffering. However, the majority of cancer survivors do not engage in regular exercise, and behavior change interventions aimed at increasing exercise behavior often fall short of achieving the recommended exercise amount of ? 150 weekly minutes of moderate-to-vigorous intensity exercise. Moreover, such interventions are rarely tested for cost-effectiveness or translated into broader use. This proposal addresses this research gap by adapting the BEAT Cancer intervention, proven to be efficacious in significantly improving the odds of meeting exercise recommendations in cancer survivors, to web-based delivery that will increase its dissemination and implementation (D&I) potential. Core intervention components (i.e., elements responsible for intervention efficacy) identified during efficacy testing will also be adapted to improve acceptability among diverse cancer survivors (e.g., older, rural residents, African-Americans). The adapted intervention will be called Reaching out for Exercise Adherence to improve Cancer survivors' Health (REACH). The 6-month REACH intervention will then be tested in 326 survivors of a variety of cancers and in whom significant proportions will be older, rural, and minority. Investigators will employ a 2-arm randomized controlled design in which survivors will be assigned with equal allocation to receive REACH or wait-list control. Our primary aim will be to determine between-arm differences with regard to meeting current exercise recommendations (? 150 weekly minutes of ? moderate intensity physical activity) measured by accelerometer. Our secondary aims will include REACH's effects on self-reported physical activity and on anthropometrics (e.g., waist circumference), lean body mass, physical function, quality of life, and biomarkers (i.e., telomerase [marker of successful aging], IFN? [immune status], and high sensitivity CRP, IL-6, and IL-10 [systemic inflammation]). Intervention cost- effectiveness will also be assessed. This proposal is critical to improving the D&I potential and public health impact of the core intervention components identified in an efficacious exercise behavior change program for cancer survivors. Increasing access to efficacious exercise behavior change interventions is critical to addressing the significant mortality, comorbidity, and psychosocial burden experienced by millions of cancer survivors each year.